What is the law on using peoples names in a blog

OK Hopefully someone on here may know some information on this and may be able to help.

This morning I received a message on facebook from someone who I dont know, but am friends with on Facebook. I thought it was spam and almost deleted it untill I seen my friends picture in it.

It was a link to a blog. Turns out it was a ex of my mate and thats how i became friends on facebook. There is a lot of detailed information in it making some very serious accusations. I cannot say if they are true or not and hope they are not.

She also goes into a lot of details about his ex who is a close friend of mine. Accusing her of stealing money, taking drugs and other fairly bad things. She use her full name, comments about her business etc.. She has sent it to me and im pretty sure she sent it to everyone else on the list of mutual friends (at least 30 people)

Question is can she do this, use such detail, names, places, etc?

The blog is based in Australia and I am in Ireland

In the US, she could be sued for defamation of character ... "the action of damaging the good reputation of someone; slander or libel."

Most of this type of stuff is reliant on physical evidence and prosecutions of accusations,
If none exist refer to Jacee's comment

Otherwise it's all hearsay nonsense which there's plenty of that on the web and most people regret posting it eventually :)